The present invention relates generally to aircraft engines and more particularly to scarf inlets for aircraft engines.
Some of the technical issues that aircraft designers must address can have significant business and economic impact. For example, aircraft designers must address the risk of foreign object damage (FOD) to aircraft engines and the operational and economic costs associated therewith. Additionally, aircraft designers also must consider the risk of excessive landing gear wheel spray ingestion into engines as well as the risk that runway debris (rocks, water, tire debris, aircraft parts, slush, gear ice, etc.) might also be thrown by the landing gear tires and ingested into the engines.
The adverse impact that engine nacelles and their inlets have on the aircraft""s lift (L) and lift-to-drag ratio (L/D) during cruise flight is another important consideration for aircraft designers. Still yet another consideration is the reduction of aircraft engine noise to alleviate its adverse impacts on the passengers as well as the airport""s neighboring communities. Indeed, the authority to increase the number of operations at many airports is often withheld because of noise-related environmental impact.
Accordingly, a need exists in the art for an apparatus and methods that reduce the probability of FOD to aircraft engines and thus mitigate the operational and economic costs associated therewith. Ideally, the apparatus would also be able to reduce the impact of aircraft engine noise on communities adjacent airports as well as mitigate the adverse impact that engine nacelles and their inlets have on aircraft lift (L) and lift-to-drag ratio (L/D) during cruise flight.
In one form, the present invention includes a scarf inlet that is rotatably supported at a forward end portion of an engine nacelle. The rotatable scarf inlet is controllably rotatable with respect to the engine nacelle to a plurality of angular positions or orientations.
In another form, the present invention provides a method of operating a jet aircraft engine on an aircraft. In one embodiment, the method comprises supporting a scarf inlet at a forward end portion of a nacelle of the engine in a manner that enables rotational movement of the scarf inlet relative to the nacelle; and controllably rotating the scarf inlet to a plurality of different angular positions depending on the a phase of operation of the aircraft. The rotatable scarf inlet is preferably rotated to an angular position in which it reduces the possibility of ingestion of foreign object into the engine during takeoff and taxi. While the aircraft is climbing after takeoff, the rotatable scarf inlet is preferably rotated to an angular position in which it at least partially shields engine noise from being transmitted downward and forward. When the aircraft is in a cruise mode of operation, the rotatable scarf inlet is preferably rotated to an angular position in which it improves at least one of compression lift and lift-to-drag ratio.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating at least one preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.